Conventional devices that share a medium between two different protocols can include combination (e.g., collocated) devices that provide Bluetooth (BT) and WLAN (e.g., various IEEE 802.11 wireless standards) communications. BT and WLAN can share a medium (i.e., 2.4 GHz band) by alternating access to the medium. BT communications include synchronous modes and asynchronous modes. For synchronous BT communications, a BT slave device can determine when BT communications with another BT device will take place and can coordinate with WLAN communications accordingly. This is not the case for some asynchronous BT communications.
In some asynchronous BT communication modes, a BT slave device cannot predict when data will be transmitted from another BT device, and so the slave device will retain control of the medium to ensure it can detect incoming data packets. As a result, WLAN communications are deferred until BT data transfers can be completed, which can greatly reduce WLAN data throughput. Such asynchronous BT communications can include those employed in the BT advanced audio distribution profile (A2DP) and asynchronous connectionless communications links (ACL), as but two examples.
FIG. 12 shows a conventional method 1200 according to an embodiment. A BT slave device can be in an asynchronous mode of operation 1203. In such a mode, the BT circuits do not know when data transmission operations will occur from another device. As a result, the BT circuits can have control the medium 1205. This prevents a collocated WLAN circuit from transmitting on the medium. The BT circuits monitor the medium to detect a packet 1207. Such an action can include monitoring each frame for an expected packet. If the packet is not received (N from 1207), the BT circuits can continue to monitor in the next frame 1209. Once a packet is detected (Y from 1207), the BT circuits can send an acknowledgement (ACK) in the slave portion of the same frame. Packets are then received and processed 1213. Such an action includes a slave device receiving one or more additional packets in subsequent frames. Once the packets cease, BT can determine if a connection has ended 1215. If a connection has not ended (N from 1215), it is assumed that more asynchronous data is expected. Thus, BT circuits can return to examining frames for packets (1209). If a connection is ended (Y from 1215), the BT circuits can relinquish the medium 1217, enabling WLAN circuits to transmit on the medium.
FIG. 13 is a timing diagram showing how a device having collocated BT circuits and WLAN circuits can limit WLAN throughput when BT circuits are handling asynchronous data transmissions. FIG. 13 shows activity of a BT master, a BT slave, a WLAN circuit, as well as medium shared between BT slave and WLAN circuit. It is understood that BT slave and WLAN circuit are formed in a same device, and a BT master is a different device that can wirelessly transmit packets for reception by the BT slave.
At 1319-1, the BT master can start a connection with the BT slave. At this time there is no contention for the medium by WLAN, so the medium is controlled by the BT slave. At 1319-3, a master can stop sending data, but a connection is not ended (e.g., more data is expected). As a result, a BT slave can maintain control over the medium, waiting to receive more data from BT master, and thus preventing WLAN from transmitting on the medium.
At 1319-5, because the BT slave controls the medium, WLAN can request access to the medium, but is denied.
At 1319-7, a master can resume transmitting data. Because BT slave has control of the media, it can immediately acknowledge such data packets and data transmissions can resume. At 1319-9, data from a master stops, but the connection is not ended. Thus, a BT slave can maintain control over the medium as it waits for more data from the BT master.
At 1319-11, WLAN can again request access to the medium, but be denied.
At 1319-13, a master can resume transmitting data. At 1319-15 data from a master stops and the connection can end. The BT slave can relinquish control of the medium, and at 1319-17 WLAN can access the medium.
It would be desirable to arrive at some way of improving data throughput in combination devices, including but not limited to, combination BT-WLAN devices.